sat-nms ACU-IDU Antenna Control System –Indoor Unit … ... TCP/IP). Any tracking functions ......

S a t S e r v i c eGesellschaft für Kommunikationssysteme mbH

© 2005, SatService GmbH www.satnms.com ACU-IDU-UM 0509-1 Seite 1/39

sat-nms ACU-IDU

Antenna Control System –Indoor Unit

User Manual

© Copyright

SatService Gesellschaft für Kommunikatiosnsysteme mbH

Hardstrasse 9

D-78256 Steisslingen

E-Mail: [email protected]

www.satnms.com

www.satservicegmbh.de

Tel +49 7738 97003

Fax +49 7738 97005



Table of Contents

Table of Contents ....................................................................................................................... 2

1. The sat-nms ACU Indoor Unit ........................................................................................... 3

1.1. Concepts ..................................................................................................................... 3

1.1.1. Tracking Modes.................................................................................................. 4

1.1.2. sat-nms ACU Indoor Unit & Outdoor Module Configuration .......................... 4

1.1.3. sat-nms ACU Indoor Unit & 3rd Party Controller Configuration ..................... 5

1.2. The ACU Main Window (with sat-nms ODM) ......................................................... 6

1.2.1. The Pointing Display.......................................................................................... 7

1.2.2. The Beacon Level Display ................................................................................. 7

1.2.3. The Tracking Status Display .............................................................................. 8

1.2.4. The ACU Subsystem Menu................................................................................ 9

1.2.5. The ODM Detailed Parameter Screens ............................................................ 10

1.2.6. The Satellite Select Screen ............................................................................... 15

1.3. The ACU Main Window (with 3rd party controller) ............................................... 16

1.3.1. The Pointing Display........................................................................................ 17

1.3.2. The Beacon Level Display ............................................................................... 18

1.3.3. The Tracking Status Display ............................................................................ 19

1.3.4. The ACU Subsystem Menu.............................................................................. 20

2. sat-nms Devices for Antenna Control System ................................................................. 22

2.1. Antenna-Pointing ..................................................................................................... 22

2.2. Antenna-Tracking..................................................................................................... 23

2.2.1. Pointing-Robot ................................................................................................. 31

2.3. SatService-ACU-IDU............................................................................................... 34

2.4. SatService-ACU-ODM ............................................................................................ 35

2.5. SatService-Beacon-Receiver .................................................................................... 35

2.6. SatService-Power-Sensor ......................................................................................... 39



1. The sat-nms ACU Indoor Unit The ACU indoor unit is a PC system based on the sat-nms M&C technology. Together with

an antenna controller and a beacon receiver it builds the sat-nms antenna control system.

Main features of this are:

• Monitoring and control of the concerned equipment.

• Satellite tracking using step track and orbit prediction tracking methods.

• Analysis and graphical presentation of the satellite tracking performance.

Using the sat-nms M&C platform as the basis, the ACU indoor unit also includes a lot of the

benefits of the basic software:

• The software is highly modularized. The subsystems interfacing the tracking engine to

the outside world may be configured to control third party products instead of the sat-

nms outdoor unit or the beacon receiver.

• The user interface is very clear and contains data analysis tools to display in which

way the antenna tracked the satellite.

• As with other implementations of the sat-nms M&C Software, the user interface is an

platform independent Java program which may by run on any other computer in the

LAN than the indoor unit itself.

• The indoor unit provides a event log database with a HTTP based interface to third

party software.

The following chapters explain the concepts behind the sat-nms antenna control system and

the architecture of specific configurations of the ACU. This is supplemented by a detailed

description of all user screens and the meaning of all adjustable parameters.

1.1. Concepts

SatService GmbH offers sat-nms ACU Indoor Unit in two general configurations:

• The first configuration is optimized to work together with the sat-nms ACU/ODM. It

utilizes all features of this device and adds a comfortable user interface with some

handy utilities to it. The basic tracking functions are handled by the ODM in this case.

The chapter 'sat-nms ACU Indoor Unit & Outdoor Module Configuration' describes

the functionality and architecture of this configuration, chapter 'The ACU Main

Window (with sat-nms ODM)' the appendant user interface. Furthermore you find a

full description of the sat-nms ACU / ODM in the document 'sat-nms ACU Outdoor

Module / User Manual'.

• The second configuration is directed to applications where the antenna pointing

controller is a third party product. In this configuration the ODM / pointing controller

is solely used to position the the antenna. All tracking algorithms are performed by

ACU indoor unit software.



Chapter 'sat-nms ACU Indoor Unit & 3rd Party Controller Configuration' describes

the functionality and architecture of this second configuration, chapter 'The ACU

Main Window (with 3rd Party Controller)' the appendant user interface.

This modularity and flexibility makes the sat-nms ACU Indoor Unit to a universal antenna

controller with sophisticated tracking capabilities which can be used with a multitude of

antennas. Due to it's configurability it can be deployed together with new antenna installations

and as an upgrade for existing antenna systems as well.

1.1.1. Tracking Modes

The sat-nms antenna control system -- regardless of the configuration used -- provides the

basic types of satellite tracking:

Step Track

In plain step track mode, the ACU performs small test steps with the antenna in regular

intervals to see if the receive level becomes better or worse for another antenna position. With

the knowledge of the antenna pattern's shape, the tracking engine computes an optimized

position from measurements taken at the old position and at the new one. Many parameters

such as the step size, averaging times and the overall repetition interval are configurable by

the operator.

Adaptive Track

The adaptive tracking mode works much like the plain step track, however the tracking engine

in background computes a mathematical model of the antenna motions from the step track

results. A great advantage of this mode is that the antenna follows the computed model even if

the beacon reception fails. With the plain step track mode, the antenna would freeze in this

case until the satellite beacon appears again.

Program Track

With the third tracking mode called program track, the antenna follows a position computed

from the satellite's ephemeris data. The tracking engine accepts Keplerian elements in NASA

2-line format or the proprietary Intelsat ephemeris data format for this. For this tracking

mode, no beacon reception is required, however the ephemeris data sets must be updated

every few days.

1.1.2. sat-nms ACU Indoor Unit & Outdoor Module Configuration

The diagram below shows the architecture of a antenna control system entirely built of sat-

nms components. The 'sat-nms ACU Outdoor Module' controls the antenna pointing and

performs the steptrack and adaptive tracking modes. The 'sat-nms LBRX Beacon Receiver'

measures the satellite beacon level and supplies this level value as a voltage to the ODM.

Both devices are controlled by the IDU through an Ethernet network (strictly spoken, the

ODM also communicates with the beacon receiver directly, but this is for synchronization

purposes only).



The indoor unit provides a comfortable graphical user interface which permits to monitor and

control the whole antenna system. Beside this, it contains the so called 'Pointing Robot', a

software module which controls the antenna pointing according to the data evaluated from

satellite ephemeris data sets or read from tables. This versatile tool superseeds the

PROGRAM-Track function built into the ODM, which is not used in this configuration.

Configuring the antenna control system in this way is the favored solution. It achieves the best

tracking results. More benefits are:

• The components of the antenna control system are optimally coordinated.

• Doing the step track locally in the ODM allows a very close timing of the operations

during a steptrack cycle, this makes the tracking less susceptible to atmospheric

variations of the beacon level.

• The tracking is completely independent from the indoor unit. If the IDU fails, the

ODM still tracks the satellite.

1.1.3. sat-nms ACU Indoor Unit & 3rd Party Controller Configuration

The diagram below shows the architecture of a antenna control system using third party

components. The 'Antenna Positioner' device solely controls the antenna pointing, it does not

perform any satellite tracking. The 'Beacon Receiver' measures the satellite beacon level. Both

devices are controlled by the IDU using arbitrary M&C interfaces (serial, TCP/IP). Any

tracking functions are performed by a software module in the sat-nms ACU IDU.



The indoor unit's main task is to perform the satellite tracking in this configuration. The IDU

reads the beacon level thru the receiver's M&C interface and directs the antenna to to tracking

steps. The tracking algorithms used by the IDU are similar to those used by the ODM, but not

exactly the same. This is mainly because there is a longer time between moving the antenna

for a test step anf reading out the beacon level.

The main advantage of this configuration is it's flexibility. The IDU is capable to do all

tracking modes with any antenna controller which can be remote controlled by the sat-nms

M&C system, the same applies for the beacon receiver. The sat-nms ACU indoor unit is a

cost effective solution to upgrade existing antenna systems with a modern, network based user

interface and a powerful satellite tracing engine.

1.2. The ACU Main Window (with sat-nms ODM)

The main screen of the sat-nms ACU Indoor Unit shows the main parameters of the antenna

tracking control similar to the front panel of a oscilloscope. The left part of the window

contains a diagram which shows the antenna movements of the past 48 hours. The most

important settings and status displays are located at the right.

The toolbar on top of the window gives access to user login/logout, the event log and some

other functions. As the ACU indoor unit inside principally is a M&C system, the toolbar is

exactly the same as for the M&C Main Window.

At the top of the right part of the window the pointing display is located. It shows the actual

antenna pointing and a strip chart of the recent history of antenna movements. Below the

pointing display you find the beacon level display It reports the actual beacon level in a

similar way. At the bottom of the right side the window contains an area with the tracking

status display. Finally, below the tracking diagram on the left side, the ACU main screen



contains the ACU subsystem menu. These buttons give you access to subsystem screens with

all detail parameters of the ACU / tracking.

1.2.1. The Pointing Display

The area in the upper right part of the window shows the actual antenna pointing and provides

entry fields to move the antenna to a given position. The example below is taken from an

antenna which is not equipped with a polarization motor, the polarization angle display is

empty therefore.

The fields labeled 'azimuth', 'elevation' and 'polarization' show the actual antenna pointing as

read out from the angle encoders. For azimuth and elevation there is also a strip chart display

of the angle. If you choose a high resolution scale for the chart, you can watch the antenna

doing the tracking steps in the chart. Click with the right mouse button into the chart to get a

pop-up menu for scales and other display options.

The 'target' fields show the actual target values. The arrow buttons below these fields permit

to adjust the antenna position in small or larger steps. This only should be done with any

tracking switched off to avoid interferences with motions initiated by the tracking engine.

1.2.2. The Beacon Level Display

Below the antenna pointing, the ACU shows the actual beacon level. The level value shown is

that one read by the ODM from the analog input. This value may differ from the level

reported by the beacon receiver directly. There is also a strip chart display of the level. The

chart moves with the same speed as the angle charts above, so you directly can watch the

influence of tracking steps to the beacon level. A click with the right mouse button into the

chart shows a pop-up menu for scales and other display options.



The screen also provides fields to set common parameters of the beacon receiver like the

receive frequency and polarization, bandwidth parameters and the frequency tracking option.

Changing the values in these fields changes the beacon receiver setting immediately.

The threshold value contained in this parameter group is the ACU/ODM level threshold rather

than the threshold parameter of the beacon receiver itself. The latter is recommended to be set

to a very low value in order to avoid level fault messages from the beacon receiver. The

beacon level threshold is to be monitored by the ACU/ODM, hence the level fault can be

synchronized with the tracking activities.

The frequency offset display in this group reports the activity of the beacon receiver's

frequency track facility, the small yellow lamp is lit while a frequency track cycle is in

progress

1.2.3. The Tracking Status Display

The lower right area of the ACU main window shows the tracking status display and the basic

tracking mode parameters.

The table below gives a short description of each parameter in this area.

tracking

mode

With this parameter you set the basic tracking mode. Available modes are OFF,

STEP and ADAPTIVE. This parameter is passed to the ODM.

interval With this parameter (upper row) you define in which intervals the ACU shall

perform tracking steps. This parameter is passed to the ODM as well.

operation

state

This field shows the general operation state of the tracking engine.

robot

tracking

This switches the pointing robot ON or OFF. If the pointing robot is activated,

the tracking mode is forced to OFF anf the antenna of moved on a path

evaluated by the robot.

interval The interval parameter in the lower row controls the update rate of the pointing



robot.

model type This status field displays the type of algorithm the pointing robot actually uses.

Possible data sources may be Keplerian elements (NASA 2-line format),

Intelsat ephemeris data or list of positions defined in a text file.

model age Displays the age of the data used by the robot. With ephemeris data sets this is

the time since the epoch of the data set. For file tracking the time stamp of the

last record in the table is used as the epoch.

Below these parameter fields a couple of fault indicators (red lamps) are located on the

screen. They report any faults of the tracking engine. The meaning of the individual faults are:

BEACON

LEVEL

The beacon level is below the threshold and one of the tracking modes STEP

or ADAPTIVE is selected. In STEP track mode the antenna freezes in this

situation, in ADAPTIVE mode the antenna is moved along the model which

has been calculated before the beacon disappeared.

PEAKING

AZ/EL

The step track peaking failed for one of the axes. The tracking engine reports

this fault if the position / beacon level pairs measured during the tracking cycle

does not match the antenna pattern curve sufficiently. This may happen if the

beacon values are too noisy or if there is no beacon reception at all and the

threshold is adjusted too low.

MODEL

FIT

If the variance of the measured peaks to the calculated model exceeds the 'jitter

threshold' value, this fault is raised. This is an indication that either the

measurement values are noisy or the model type is not appropriate for the

satellite's motion.

MODEL

RESET

If the ODM recognizes a 'MODEL FIT' fault at three consecutive tracking

cycles, it presumes the model to be invalid and resets the model. This voids all

recorded step track positions (they remain visible in the diagrams) and resets

the tracking to the learning phase where no model is available.

1.2.4. The ACU Subsystem Menu

The icons below the tracking diagram are the ACU subsystem menu. They give access to

some less frequently used parameters of the antenna control system.

Clicking to the ODM icon opens a window which permits access to all parameters of the

ODM directly. Also the the color of the icon signals the fault state of the ODM device. With

the ODM device window there are a couple of parameters which control the behavior of the

tracking subsystem. Chapter 'The ODM Detailed Parameter Screens' gives a detailed

description of them.



The BCRX icon opens a window directly to operate / configure the beacon receiver attached

to the ACU. This window is required to set some beacon receiver parameters which are not

accessible thru the application main screen.

The 'VIEW PLOT' button opens a separate graphical Y/T display window which gives more

detailed information about what the tracking engine did during the recorded hours. It provides

variable scales, and permits to display additional information. The display shows either the

azimuth or the elevation pointing found at the beginning of each tracking step together with

the beacon level measured at this time. The following additional information may be included

to the diagram:

This button has no function in this configuration.

The main pointing graph (light green) always shows the pointing the antenna was really

moved to. This is the smoothed position if smoothing is activated. If this toolbar button is

pressed, the diagram includes the evaluated peak positions as a faded, dark green graph.

Clicking to the 'SATELLITE SELECT' button opens a window which lets you store and recall

the position and the tracking parameters of several satellites. Also the ephemeris data for the

pointing robot are entered here. Chapter 'The Satellite Select Screen' explains the functions of

this screen.

1.2.5. The ODM Detailed Parameter Screens

The ODM detailed parameter screens are part of the M&C device window for the SatService

ACU/ODM. This window integrates all status and control parameters which are available for

the ODM. To monitor and control the tracking functions of the ACU, the following two

screens are important:

Clicking to the meter symbol in the toolbar shows the tracking state page. It displays a

number of state parameters which report what the tracking engine actually does.



azimuth The actual azimuth pointing.

elevation The actual elevation pointing.

level The actual beacon level (read from the ODM's analog input).

az model The model type the ODM uses for the azimuth axis in ADAPTIVE mode if the

beacon is lost. The value is displayed all the time, even if the beacon level is

OK.

el model The same for the elevation axis.

model age This displays the time since the adaptive models have been updated the last

time. The value normally is zero, if the beacon disappears it counts the time the

antenna is tracked using the model.

az

amplitude

The amplitude of the azimuth motion as a percentage of the antenna's 3 dB

beamwidth. The ODM approximates the motion by a simple sine function to

determine the amplitude.

el

amplitude

The amplitude value for the elevation axis.

time in

memory

The time span covered by the tracking data the ACU has in it's memory.

az jitter The variance of all steptrack positions in memory with respect to the modeled

values (azimuth). This is a measure how good the model fits. The jitter value is

in percent if the antenna's 3 dB beamwidth. The 'jitter threshold' setting refers

to the 'az/el jitter values.

el jitter The same for the elevation axis.

X/Y PLOT Clicking to this button opens a separate window showing the same X/Y

diagram as displayed in the main window.

operation

state

Shows what the tracking engine actually is doing.

Y/T PLOT Clicking to this button opens separate window showing the same X/T diagram

as can be accessed from the main window.

Clicking to the device control symbol in the toolbar shows the tracking parameter page.

Beside the tracking parameters shown in the application main window this page displays all

adjustable parameters of the tracking subsystem.



mode The tracking mode parameter selects the tracking method, the ACU

actually uses. Possible selection are:

OFF No tracking is performed.

STEP Step track mode. In regular intervals, the antenna

performs small search steps to optimize the pointing.

ADAPTIVE The adaptive tracking mode works the same way as step

track, but it additionally is capable to predict the

satellite's position when the beacon reception fails. It

computes mathematical models of the satellites motion

from the step track results recorded over a certain time.

PROGRAM The program tracking mode is offered here only for

compatibility purposes only. In conjunction with the IDU

the pointing robot should be used rather than the program

track mode of the ODM.

A full description of the tracking functions used in the sat-nms ACU is

given in chapter '5.0 Theory Of Operation' of the ACU/ODM manual.

interval The interval time specifies how often the ACU shall perform a step track

cycle. The value is to be entered in seconds. In fact, the parameter does

not specify a cycle time but the sleep time between two tracking cycles.

This means, the true cycle time is the time the ACU needs to perform one

step track cycle plus the time entered here. 300 seconds (5 minutes) is a

good starting value for this parameter. Inclined orbit satellites probably

will require a shorter cycle time, very stable satellites can be perfectly

tracked with one step track cycle every 15 minutes (900 seconds).

step size The tracking step size is a very important parameter for the performance

of the tracking. It defines the size of every depointing step, the ACU

makes in order to find out where the optimal antenna pointing is. Setting

too high values will cause significant signal degradations during the step

track cycle because the antenna moves a too large amount away from the



satellite. Setting the value too small will let the beacon level jitter mask

the level differences caused by the test steps, the antenna will not track

the satellite properly.

The step size is specified as a percentage of the antenna's half 3dB

beamwidth. The ACU calculates the beamwidth from the antenna

diameter and the beacon frequency. Expressing the step size in this

relative way keeps the value in the same range, regardless of th type of

antenna. The recommended value for this parameter is 15-20%. You may

want to start with 20% and try to reduce down to 15% if the signal

degradation during tracking becomes too high.

The tracking step size is a common parameter for both axes. If both axes

behave differently, you can tweak the antenna diameter settings in the

setup. Specifying a larger diameter makes the ACU using a smaller step

size for this axis.

If the tracking step seem to be completely out of range, you should check

if the beacon frequency is set properly. The frequency must be the true

receive frequency at the antenna, entered in MHz, not an L-band

frequency or other IF.

averaging When measuring the beacon level, the ACU takes a number of samples

and averages them. The standard value of 5 samples normally should not

be changed. Larger values will slow down the ACU execution cycle.

meas delay During a steptrack cycle, the ACU positions the antenna to a certain

offset and then measures the level. Between the moment when the

antenna reached commanded position and the beacon level measurement

the ACU waits some time to let the beacon level settle. The optimal delay

value depends on the beacon receiver's averaging / post detector filter

setting and is a quite critical for the steptrack performance.

If the delay is too short, the beacon voltage does not reach its final value,

the steptrack does not properly recognize if the signal gor better or worse

after a test step. If the delay is too long, the impact of fluctuation to the

measures level grows and may cover the small level difference caused by

the test step. With the sat-nms LBRX beacon receiver, best results are

achieved if the receiver is set to 0.5 Hz post detector filter bandwidth and

a measurement delay of 1500 msecs

recovery delay After the the ACU has done the tracking steps for the elevation axis, it

waits some time before it starts tracking the azimuth axis. This is to let

the beacon level settle after the final position has been found. A typical

value for this parameter is 4000 msecs

smoothing This parameter controls the smoothing function. Setting it to zero

disables smoothing. Smoothing lets the ACU point the antenna to

positions evaluated from a simple model calculated from the step track

peaks of the recent few hours. To understand the functionality of the

smoothing function you may want to read chapter '5.3.3 Smoothing' in



the ACU/ODM manual.

level threshold If the beacon level falls below this threshold value, the ACU does not

perform a step track cycle. If the level falls below the threshold during

the steptrack cycle, the cycle gets aborted.

If the ADAPTIVE tracking ist enabled and there is enough data in the

tracking memory, the ACU computes a mathematical model from the

stored data and predicts the antenna pointing position from the

extrapolation of the model. If the tracking mode is set to 'STEP', the ACU

leaves the antenna where it is if the beacon level drops below the limit.

Adjusting the threshold level that adaptive tracking is switched as

expected must be done carefully and may require some iterations,

specially if the beacon is received with a low C/N. A good starting value

for the threshold is 10 dB below the nominal receive level or or 2 dB

above the noise floor the beacon receiver sees with a depointed antenna,

whatever value is higher.

To turn off the monitoring of the beacon level (this in fact inhibits the

adaptive tracking), simply set the threshold the a very low value (e.g. -99

dBm)

jitter threshold If the jitter value of at least one axis exceeds this threshold, the ACU

raises an 'model fault'. If this happens three consecutive times, the ACU

resets the models of both axes. Adaptive tracking will be possible not

until 6 hours after this happens.

A typical threshold value is 20%, this will detect very early that a model

does not fit to describe the satellite's motion. If this value causes false

alarms too often, you may want to raise the threshold to 50%. Setting it to

0 switches the threshold monitoring completely off.

az max model

el max model

These settings let you limit the adaptive model to a simpler one, the ACU

would choose by itself. The maximum model type can be set individually

for each axis. Normally you will set both axes to 'LARGE', which leaves

the model selection fully to the the ACU's internal selection algorithms.

In cases where the ACU seems to be too 'optimistic' about the quality of

the step track results, the maximum model on one or both axes may be

limited to a more simple and more noise-resistant model. Specially

inclined orbit satellites which are located close to the longitude of the

antenna's geodetic location may require this limitation for the azimuth

axis. With such a satellite, the elevation may move several degrees while

the azimuth shows almost no motion.

CLR MEM Clicking to this button clears the tracking memory. You should do this

when you start to track a new satellite. Clearing the tracking memory

about half an hour after tracking started significantly improves the quality

of the first adaptive tracking model which will be evaluated after 6 hours

of tracking. This is because the model does not get disturbed by the first



search steps the antenna does until the optimal pointing to the satellite is

found.

1.2.6. The Satellite Select Screen

The satellite select screen combines two functions for pointing the antenna to a satellite's

position: The entry of ephemeris data to the pointing robot and the administration of the

ACU's target memory locations.

The upper part of the screen is used to feed the pointing robot with the ephemeris data this

requires to point the antenna to the satellite's position.

The usage is very simple: Copy the ephemeris data from e.g. your web browser window into

the 'ephemeris data' field and click to the 'CALCULATE' button. The software tries to identify

and parse the data and sets the informational fields on this right site to the values computed

from the data. The 'azimuth' / 'elevation' / 'polarization' files show the antenna pointing which

actually lets the antenna look to the satellite. The values below describe the type and the age

of the ephemeris data set.

The pointing robot is capable interpret several types of ephemeris data including Keplerian

elements in NASA 2-line format, Intelsat data, plain orbit positions and tables of az/el/pol

value triples. The description of the Pointing-Robot logical devices describes the recognized

data formats in detail.

The button 'GO' lets you make the pointing robot assist you in finding a satellite: Enter the

satellite's nominal orbit position (or it's ephemeris data, if known), then click to

'CALCULATE', verify the calculated antenna pointing anf finally click the 'GO' to let the

antenna move to this position.



The lower part of the screen manages the permanent storage of satellite parameters. Up to 24

satellites may be stored. The target memories store the antenna pointing and all tracking

parameters. They are physically stored at the ODM's flash memory. If the ODM gets

replaced, the stored positions are lost.

The ACU also stores the beacon receiver settings together with a target. These are stored at

the beacon receiver itself. The ODM, when receiving a command to store or recall a target

memory, sends a command to beacon receiver to do the same.

Recalls this preset. The antenna is moved to the stored position, all tracking parameter

are set as stored and the beacon receiver's parameters are set from the values stored with

the preset. The tracking memory is cleared if a target memory is recalled. Only if the

target number 0 is recalled, the tracking memory is restored to the state when this target

was saved.

Stores the actual settings in this preset. The satellite name, the actual pointing and all

tracking parameter are stored in the preset. The beacon receiver parameters are stored as

well.

The preset memory with this number is deleted.

The target memory location 0 is a special one. Unless the other memory locations, this first

one stores the contents of the tracking memory and all temporary tracking data like models

etc. together with the position and parameters.

This makes the first memory location dedicated to the short time storage of a satellites

tracking state, when another satellite shall be tracked for a couple of hours. Example:

The antenna is tracking satellite A for a long time, the tracking memory is filled with 70 hours

of step track data for this satellite. During a maintenance phase, the antenna shall temporarily

track satellite B. With the target 0 memory you would handle this situation as follows:

1. Store the actual state as target 0 before the antenna is moved to point to satellite B.

2. Move the antenna to point to satellite B, either by recalling the target memory for this

satellite or by pointing the antenna and clearing the tracking memory manually.

3. Let the antenna track satellite B for a couple of hours as needed.

4. No return to satellite A by recalling the target memory 0. This points the antenna back

to satellite A and restores the tracking memory data for this satellite.

You should consider that it only makes sense to reuse the stored tracking data if there is less

than twelve hours of discontinuity in tracking the satellite. If too much data is missing,

clearing the tracking memory wil give the more reliable results.

1.3. The ACU Main Window (with 3rd party controller)

The main screen of the sat-nms ACU Indoor Unit shows the main parameters of the antenna

tracking control similar to the front panel of a oscilloscope. The left part of the window

contains a diagram which shows the antenna movements of the past 48 hours. The most

important settings and status displays are located at the right.



The toolbar on top of the window gives access to user login/logout, the event log and some

other functions. As the ACU indoor unit inside principally is a M&C system, the toolbar is

exactly the same as for the M&C Main Window.

At the top of the right part of the window the pointing display is located. It shows the actual

antenna pointing and a strip chart of the recent history of antenna movements. Below the

pointing display you find the beacon level display It reports the actual beacon level in a

similar way. At the bottom of the right side the window contains an area with the tracking

status display. Finally, below the tracking diagram on the left side, the ACU main screen

contains the ACU subsystem menu. These five buttons give you access to subsystem screens

with all detail parameters of the ACU / tracking.

1.3.1. The Pointing Display

The area in the upper right part of the window shows the actual antenna pointing and provides

entry fields to move the antenna to a given position. The example below is taken from an

antenna which is not equipped with a polarization motor, the polarization angle display is

empty therefore.



The fields labeled 'azimuth', 'elevation' and 'polarization' show the actual antenna pointing as

read out from the angle encoders. For azimuth and elevation there is also a strip chart display

of the angle. If you choose a high resolution scale for the chart, you can watch the antenna

doing the tracking steps in the chart. Click with the right mouse button into the chart to get a

pop-up menu for scales and other display options.

The 'nominal' fields define the nominal antenna pointing for the actual satellite. The nominal

pointing describes the center of the satellite's path over 24 hours.

• If you store the antenna pointing and the tracking parameters as a ACU preset, the

software stores the nominal pointing. If you recall the preset, the software moves the

antenna to the stored pointing and starts tracking there in the operation mode stored

with the preset.

• The antenna moves to the nominal position, if you click to the 'RESET POSITION'

button.

• The absolute tracking limits configured in the TRACKING subsystem refer to the

nominal antenna pointing.

If you change a nominal pointing value while the antenna has tracking switched on, this only

moves the reference point for the tracking limits. The antenna is under control of the tracking

engine and does not move due to this change.

If the ACU tracking mode is set OFF, the antenna behaves differently. In this case changes of

the nominal value let the antenna move immediately to the selected position.

Finally, the 'offset' fields indicate the actual difference between the real antenna pointing and

the nominal position.

1.3.2. The Beacon Level Display

Below the antenna pointing, the ACU shows the actual beacon level. There is also a strip

chart display of the level. The chart moves with the same speed as the angle charts above, so

you directly can watch the influence of tracking steps to the beacon level. A click with the

right mouse button into the chart shows a pop-up menu for scales and other display options.



The screen also provides fields to set the beacon frequency and the receive polarization (the

latter is not supported by antenna where the example picture has been taken from). Changing

the values in these fields changes the beacon receiver setting immediately.

If you are using a third party beacon receiver which is not controlled by the ACU indoor unit,

you nevertheless have to set the beacon frequency here. This is because the tracking software

takes the frequency into account when estimating the antenna receive pattern and from this

the tracing step sizes.

1.3.3. The Tracking Status Display

The lower right area of the ACU main window shows the tracking status display and the basic

tracking mode parameters.

The table below gives a short description of each parameter in this area. The all refer to the

TRACKING subsystem, this chapter gives a more detailed description of the tracking.

satellite

name

The name of the satellite you are tracking.

nominal

orbit

The nominal orbit position of the satellite.

orbital

model

The type and age of the orbital model the ACU uses for the PROGRAM

track mode. During ADAPTIVE tracking, the the number of hours in

memory are displayed here.

tracking

mode

With this parameter you set the basic tracking mode. Available modes are

OFF, STEP, ADAPTIVE and PROGRAM.

interval With this parameter you define in which intervals the ACU shall perform

tracking steps.

operation

state

This field shows the general operation state of the tracking engine.

tracking step This field tells what the tracking engine is doing actually in this moment.



RESET

POSITION

Moves the antenna back to the nominal pointing values. If you do this in

ADAPTIVE or in PROGRAM track mode, the antenna will return to the

estimated pointing with the next tracking step. With STEP track mode, the

antenna starts tracking at the nominal pointing if you click to this button

RESET

MEMORY

Clicking to this button clears the tracking memory, the ACU remembers to

estimate the antenna pointing in ADAPTIVE mode. You should do this if

you change tracking to another satellite or if you recognize a significant

repositioning of the satellite.

1.3.4. The ACU Subsystem Menu

The five icons below the tracking diagram are the ACU subsystem menu. Although looking

unimposing, this menu is very important as it gives you access to all parameters of the ACU's

subsystems.

Clicking to the TRACKING icon launches a window which shows all parameters of the

tracking subsystem. The color of the icon tells about the fault state of the tracking engine

(green = OK, red = FAULT). You open the TRACKING subsystem window in order to

• save and recall satellite presets.

• adapt low level tracking parameters like step sizes, averaging times etc.

• enter ephemeris data for antenna positioning or PROGRAM track mode.

The ODU icon opens a window to operate / configure the antenna positioner device. Normally

it will not be necessary to access the positioner directly in this ACU configuration, moreover,

it might mess up the tracking process if you command the antenna directly. There are

however a few situations where you want to see all antenna parameters:

• The positioner shows a fault (red icon) and you want to know what the reason for the

fault is.

• You want to move the antenna manually in small steps, e.g for the pointing calibration

or for measurements. The SatService ACU ODM device window provides step

movement buttons which help you to do this efficiently.

The BCRX icon opens a window directly to operate / configure the beacon receiver attached

to the ACU. This window is required to set other beacon receiver parameter than the

frequency or receive polarization.

The 'VIEW PLOT' button opens a separate graphical Y/T display window which gives more

detailed information about what the tracking engine did during the recorded 48 hours. It

provides variable scales, and permits to display additional information. The display shows

either the azimuth or the elevation pointing found at the beginning of each tracking step

together with the beacon level measured at this time. The following additional information

may be included to the diagram:



If this toolbar button is pressed, the diagram shows the search step and the beacon level

change resulting from this as a dimmed peak at the left edge of each data point. You can

easily monitor the signal degradation which is caused temporarily by the tracking search

steps with this function enabled.

If this toolbar button is pressed, the diagram includes the evaluated peak positions. In

STEP track mode, this actually is the location where the antenna gets moved to. In

ADAPTIVE tracking mode, the antenna moves to the location resulting from the

mathematical model which is computed from the step track peaks. In the latter case, the

peak positions may be interpreted as the actual difference between the modeled pointing

and the peak position.

Clicking to the 'VIEW LOG' button opens a window where the program shows a live report

what the tracking engine actually is doing. The log in this window is cleared with each new

tracking step. If 'Y/T PLOT' diagram shows many unsuccessful tracking steps, watching the

log reports may give an explanation why the tracking engine discards so many steps.



2. sat-nms Devices for Antenna Control System

2.1. Antenna-Pointing The Antenna-Pointing logical device is a 'high level' driver for motor driven antennas. It is

used together with a driver for the type of antenna controller used.

While the plain driver for the antenna controller simply supports to set the

azimuth/elevation/pol-pffset parameters of the antenna, the Antenna-Pointing logical device

extends this with additional capabilities:

• It permits to set the antenna pointing by supplying a satellite orbit position. The

Antenna-Pointing logical device computes the antenna pointing from the satellite

position and sends these values to the low level antenna driver.

• It maintains a list of satellite names, stored together with the orbit position of each

satellite and the (manually fine tuned) antenna pointing values for each satellite. The

standard user interface for the Antenna-Pointing logical device contains a comfortable

tool to handle this list.

Device window pages

The following table shows which device window pages are available with this individual

device type. Tool-bar functions not mentioned here are described at the general description of

device windows.

Contains the antenna pointing values, the selected satellite name and the orbit position of

this satellite. You should use this page if you want to move the antenna to a certain orbit

position.

The list of satellite positions. You can select a satellite to move the antenna to with this

page and you can maintain the satellite list.

The device info page.

The maintenance page. Configuration parameters described below are set at this page.

Configuration parameters

At the maintenance page of the device window there are a couple of configuration parameters

which must be set to make the Antenna-Pointing device work properly.

parameter description

azId The message ID controlling the antenna's azimuth parameter.

elId The message ID controlling the antenna's elevation parameter.

polId The message ID controlling the antenna's polarization parameter.

longitude The antenna's longitude (degree east). Provide this value with an accuracy of

0.01° to ensure a precise orbit to pointing calculation.



latitude The antenna's latitude (degree north). Provide this value with an accuracy of

0.01° to ensure a precise orbit to pointing calculation.

Remarks

1. To make the antenna move to a satellite already stored in the list, double click to the

satellite's entry in the - page.

2. Pressing the right mouse button on a satellite's entry in the list opens a context menu

offering all funktions to manage the satellite list.

3. When entering a new satellite to the list, first move the antenna to it's calculated

position by entering the satellite's orbit position at the - page. Optimize the antenna

pointing. Then switch to the - page, add a new entry to the list and update this entry

with the current antenna pointing.

Satellite position file

The Antenna-Pointing device stores the satellite positions in a text file in the base directory of

the M&C/VLC software. It is named "XXXX.txt" where XXXX is the name of the Antenna-

Pointing logical device. The file contains the satellite list as a table of semicolon separated

fields. It may be imported by common spread sheet programs this way. The table columns are

defined as follows.

1. satellite name

2. orbit position (deg. east)

3. antenna azimuth

4. antenna elevation

5. antenna polarization offset

Be aware, that the numeric values are stored with a decimal dot (##.###), regardless of the

default locale of your computer.

2.2. Antenna-Tracking The Antenna-Tracking logical device is a 'high level' driver for motor driven antennas. It is

used together with a driver for the type of antenna controller used. To operate the device in

step track modes, also a beacon receiver is required. The Antenna-Tracking device provides

three mayor tracking modes:

STEP In plain step track mode, the device performs small test steps with the antenna

in regular intervals to see if the receive level becomes better or worse for

another antenna position. With the knowledge of the antenna pattern's shape,

the tracking engine computes an optimized position from measurements taken

at the old position and at the new one. Many parameters such as the step size,

averaging times and the overall repetition interval are configurable by the

operator.

ADAPTIVE The adaptive tracking mode works much like the plain step track, however the

tracking engine in background computes a mathematical model of the antenna

motions from the step track results. After a tracking step the antenna is moved

to the position computed from this model rather than to the measured



maximum. This significantly smoothes the path at which the antenna follows

the satellite. Another great advantadge of this mode is that the antenna follows

the computed model even if the beacon reception fails. With the plain step

track mode, the antenna would freeze in this case until the satellite beacon

appears again.

PROGRAM With the third tracking mode called program track, the antenna follows a

position computed from the satellite's ephemeris data. The tracking engine

accepts Keplerian elements in NASA 2-line format or the proprietary Intelsat

ephemeris data format for this. For this tracking mode, no beacon reception is

required, however the ephemeris data sets must be updated every few days.

Device window pages



device windows.

Basic tracking parameters

The primary page contains the basic tracking parameters like the nominal antenna

position or the mayor tracking mode. This page also gives access to the logging and

analysis tools built into the tracking device. The most important parameters are explained

below:

satellite name: This ist the name of the satellite as it appears in the list of stored targets.

When you read in ephemeris data which contains a satellite name, the latter gets copied

into this field. You may however enter any other name.

nominal orbit: With this parameter the satellite's nominal orbit position is specified.

There are two applications for the nominal orbit value in the software: The tracking

device is capable to evalues the antenna pointing angles for the orbit position, you may

move the antenna to the resulting position in order to find a new satellite quickly. Also

the orbit value is used to identify and sort satellites in the target list.

The nominal orbit position has to be entered as 'deg. east' To specify a satellite at 10°

West, either enter -10.0 or 350.0, the software accepts both notations.

tracking mode: With this parameter you select the major tracking mode. Available

modes are:

STEP Plain step track mode.

ADAPTIVE Step track with mathematical model assistance / backup.

PROGRAM Program track following given ephemeris data.

interval: Defines the overall tracking interval. The tracking device performs it's steps not

faster than defined with this parameter. If an optimization step takes longer than this

interval, this is not treated an a fault. The tracking device will start the next step



immeiately after the first one has finished. Set this value to 0 in order to force the

tracking to operate at a maximum rate.

The effective duration of one optimization step primarily depends on the integration

times and delays defined with the advanced step track parameters. But also the

fluctuation of the beacon level reading has an impact to the duration of a tracking step. If

the standard variation of the readings will exceed a configurable threshold, the tracking

algorithm will try to repeat the measurement several times.

az/el nominal: These fields define the nominal position of the antenna for this satellite.

The nominal position is the center of the box in which the antenna tracks the satellite.

The size of this box is set on the 'advanced tracking parameters' page described below.

The nominal position also is that one the antenna moves to, if the satellite's tracking

settings get recalled from a preset memory.

Changing one of the nominal position values while the tracking mode is 'OFF'

immediately moves the antenna to the given position. With tracking enabled, changing a

nominal position value does not move the antenna, only the box limits are shifted

accordingly.

polarization: The polarization value directly controls the antenna's polarization offset

motor (if available). None of the tracking algorithms changes this value, in must be

optimized manually when a satellite is going to be tracked the first time.

beacon frequency: This parameter controls the beacon receiver's receive frequency. The

true RF receive frequency value is required, not an L-band frequency. It is necessary to

enter this value even if the beacon receiver is not controlled by the tracking M&C

system. This is because the tracking engine uses the beacon frequency to compute the

tracking step sizes.

beacon pol.: With beacon receivers which are capable to switch the input polarization,

this parameter permits to select the polarization plane of the beacon to receive.

Y/T PLOT: Clicking to the 'Y/T PLOT' button opens a window which shows a diagram

of the antenna movement and the beacon level over the time. If you leave this window

opened, it gets updated with each tracking step the antenna makes. See the paragraph

'built in analysis tools' below for further information.

X/Y PLOT: Clicking to the 'X/Y PLOT' button opens a window which shows a diagram

of the antenna movement in both axes. If you leave this window opened, it gets updated

with each tracking step the antenna makes. See the paragraph 'built in analysis tools'

below for further information.

STEP LOG: Clicking to the 'STEP LOG' button opens a window where the program

shows a live report what the tracking engine actually is doing. The log in this window is

cleared with each new tracking step. If 'Y/T PLOT' diagram shows many unsuccessful

tracking steps, watching the 'STEP LOG' reports may give an explanation why the

tracking engine discards so many steps.



RESET POS: Moves the antenna back to it's nominal position.

RESET MEM: Clears the tracking memory used by the ADAPTIVE tracking mode.

orbital model: Displays the type and age of the orbital model used by the PROGRAM

tracking mode. While in ADAPTIVE tracking mode 'ADAPTIVE' is displayed.

operation state: Reports the actual operation state of the tracking engine. This mainly

reflects the major tracking mode, but also contains some additional information, e.g.

which type of ADAPTIVE model the tracking engine actually uses.

tracking step: Reports the tracking step which recently has been done. This exactly

matches the last line of the 'STEP LOG' display.

tracking offset: These fields report the actual offset of the antenna pointing from the

nominal position.

beacon level: Displays the beacon level as actually read from the beacon receiver.

Satellite list

The satellite list page permits to store tracking settings in a target memory pool which is

unique to this instance of the Antenna-Tracking device. This is unlike the standard

device preset function if the sat-nms software which stores device settings for all

instances of one device type at a central place. The following functions are provided by

this page:

Save actual satellite: Clicking to this button stores the actual tracking parameters

together with the nominal antenna pointing into a data file named after the actual satellite

name followed by the nominal robit position. If a file of this name already exists, it gets

replaced.

Delete seleted entry Deletes the selected (yellow colored) target memory file.

Load selected parameters Loads all tracking parameters except the nominal antenna

pointing from the selected target memory. This is intended to be used to copy the

tracking settings from an already known satellite to a new one, which actually is being

set up.

Track selected satellite Loads all settings including the nominal antenna pointing and

the tracking mode. Moves the antenna to the nominal pointing position and starts the

selected tracking mode there.

Orbital model

At this page you may define an orbital model for the satellite which is used with the

PROGRAM tracking mode. The orbital model also may be used to find a satellite more

precisely than by it's nominal orbital position.

The tracking engine accepts either Keplerian elements in NASA 2-line format or Intelsat



ephemeris data. The software automatically recognized the data format and chooses the

appropriate orbital model. A common source for actual Keplerian ephemeris data is

www.celetrak.com, weekly updated Intelsat orbital data may be found on the Intelsat

web site.

The easiest way to enter the orbital data to the tracking system is by copy & paste from

the source web site. Clear the orbital data field, mark the desired orbital data in the web

browser window and copy it into the orbital data entry field (use CTRL-C/CTRL-V on

Windows based PC, the middle mouse button on Linux boxes like the sat-nms ACU

indoor unit. For Intelsat data, copy the whole web page which shows the ephemeris data

set. For Keplerian data copying the two lines containing the element data is required.

When using data from Celestrak, you optionally may copy also the comment line above

the element data, the satellite name will be adapted automatically in this case.

Once you entered / copied the orbital data and change the input focus to another field, the

software analyzed the data and updates the fields at the top of the page. The 'recognized

orbital model' shows the type and age of the interpreted ephemeris data. The 'satellite

name' and 'nominal orbit' are updated accordingly, if this information is present in the

entered data. If you select the PROGRAM tracking mode on the primary parameter page,

the antenna follows the position of the satellite as computed from the ephemeris data.

Using the buttons below the orbita ldata entry field you may compute the actual antenna

pointing either from the entered ephememeris data or from the satellite's nominal orbit

position. Clicking to the large button at the bottom move the antenna to the computed

position. This function is intended to be used to find a new satellite quickly. If there is no

orbital data available for the satellite you search, you may enter it's nominal orbit

position directly and compute the antenna pointing from this.

The accuracy of the calculated antenna positions heavily depends on the antenna pointing

calibration and on the accuracy of the antenna's geodetic location as defined with the

configuration parameters.

Advanced step track parameters

This page contains a number of parameter which are used to tune the tracking algorithm.

Most of these parameters affect the STEP and ADAPTIVE tracking modes as well.

step size: This parameter controls the sizes of the search steps the tracking engine

performs in the STEP and ADAPTIVE modes. With the step size set to 100%, the

elevation test step is one half of the antenna's 1dB bandwidth. The azimuth step size is

computed the same way, but divided by cos(elevation) to deskew look angle to the

satellite. The antenna's beamwidth (approximately) is computed from the beacon

frequency and the antenna diameter. A good initial value for the step size is 60%.

settling time: The settling time is the time the tracking engine waits after it issued an

antenna pointing command until it takes the first sample of the beacon level. Specially

with small steps of the antenna position, the tracking engine has no real feedback when

the antenna has reached it's final position. This delay time is used to ensure that the

antenna pointing command has been executes and the beacon level has settled.



step mode: In STEP mode, this parameter controls how the tracking engine selects the

direction of a search step. With the SLOW step mode, search steps alternately are made

in the one or the other direction. This step mode gives good results with satellites that

move only a small amount. With the FAST step mode, each search step is made in the

same direction of the last successful optimization step. With any unsuccessful step the

direction changes. This mode is recommended to track inclined orbit satellites, because

the tracking does not perform search steps against the satellite movement in the majority

of cases. In the ADAPTIVE tracking mode, the tracking engine observes the step mode

selection only as long as it cannot compute a usable model from the recordes steptrack

data. Later it uses the the modeled antenna pointing to decide where to go for a search

step.

max optimization: The step track algorithm uses the measured beacon levels before a

search step and after it together with some knowledge about the shape of the antenna

beam to compute the peak location. Unexpected variations of the beacon level may

disturbe the measurement and may result to a wrong peak evaluation. To minimize the

impact of this to the antenna pointing, the tracking algorithm limits the amount of an

optimization step to this value. Setting this parameter to 0% forces the tracking engine to

limit the peak position to a window between the antenna positions before and after the

search step. Increasing the 'max optimization' parameter widens this window at both

edges with the actual search step size multiplied by the 'max optimization' value.

With the ADAPTIVE tracking mode this parameter is used, too. Here however it acts as

a fault threshold: If a peak is outside, is is marked as invalid and not included to the

tracking model computation.

az/el search step: These fields show the actual search step sizes as absolute angles for

you orientation. The fields get updated each time you change the 'step size' parameter.

az/el window: These parameters define a rectangular window around the nominal

antenna position. The tracking engine limits the optimization movements to this window.

beacon averaging time: This parameter defines the time, while samples read from the

beacon receiver get averaged to achieve one beacon level value. Recommended values

are between 15 and 30 seconds, if the beacon receiver itself performs an effective

averaging/smoothing of the level reading, shorter values may be possible.

max standard deviation: While the program averages the beacon level readings, it also

computes the standard deviation of the reading as a measure of the (short term) stability

of readings. If the standard deviation exceeds this limit, the measurement is discarded.

max signal drift: Before performing a search step, the tracking algorithm requires two

beacon measurement series to differ not more than the value defined here. Otherwise the

beacon level is assumed to drift, the search step is postponed or canceled.

max drop in search step: If with a search step the beacon level drops more than the

value set here, the antenna moves back to the previous or predicted position, no peak

evaluation is done.



min beacon level: If the measured beacon level falls below this value, a beacon level

fault is rised and the measurement is marked as invalid. With the STEP tracking mode no

tracking is performed until the beacon level is above the threshold again. In ADAPTIVE

mode, the tracking engine tracks the satellite following the mathematical model made

from the step track peaks.

Faults and fault mask

Beacon receiver: The beacon receiver device states a fault. This may be a hardware fault

or a loss of signal. It is recommended to switch of any level threshold monitoring at the

beacon receiver and let the tracking device monitor the beacon level. The tracking device

applies threshold monitoring only during the measurement phases, signal dropouts during

the antenna movement phases are ignored.

Beacon level: The measured beacon level is below the threshold set at the advanced step

track parameters page.

AZ/EL window limit: The recent step track peak found is outside the window limits set

at the advanced step track parameters page. The antenna has been moved to the window

limit rather than to the peak position. The fault stays active until the next tracking step.

Antenna: The antenna positioning controller states a fault. This may be a motor failure,

limit switch or another specific antenna fault.

Seach step size: The tracking engine is not capable to compute a valid tracking step size

from the given data. This happen if either the antenna diameter (a setup parameter) or the

beacon frequency is not set properly. The fault stays active until the missing value is set.

AZ/EL Model match: In ADAPTIVE tracking mode, a tracking step found a peak

which considered to be invalid at it is too far away from the position computed by the

model. The fault stays active until the next tracking step.


The maintenance page. The configuration parameters described below are set at this

page.



which must be set to make the Antenna-Tracking device work properly.


config.azimuthId Enter here the parameter ID of the azimuth target value the tracking

unit shall use. Example: 'ODU.azimuth'

config.stateAzId Enter here the parameter ID of the azimuth read out value the

tracking unit shall use. Example: 'ODU.state.az'

config.elevationId Enter here the parameter ID of the elevation target value the tracking

unit shall use. Example: 'ODU.elevation'



config.stateElId Enter here the parameter ID of the elevation read out value the

tracking unit shall use. Example: 'ODU.state.el'

config.polarizationId Enter here the parameter ID of the polarization offset target value the

tracking unit shall use. The tracking unit does no polarization,

however a fixed polarization offset value is stored together with each

target. Example: 'ODU.polarization'

config.antennaFaultId Enter here the parameter ID of the antenna fault, the tracking unit

shall monitor.

config.bcrxFreqId Enter here the parameter ID of the beacon receiver frequency setting.

The tracking unit sends the receive frequency stored with a target to

this parameter (RF frequency, not L-band). Leave this field empty, if

the beacon receiver frequency cannot be controlled through the sat-

nms software. Please note, that in the tracking unit the beacon

frequency must be set to the correct value even if it is not passed to

the beacon receiver. This is because the tracing unit computes the

step track search sizes from the beacon frequency.

config.bcrxLevelId Enter here the parameter ID of the beacon receiver level reading. The

value is expected to be a receive level in dBm or a C/N value [dB].

To read the analog output value of a tracking receiver, you need an

external device which reads this voltage and converts the readint to

dBm. The sat-nms Antenna Control Unit ODM is capable to do this.

config.bcrxFTrackId If you are using a sat-nms L-band beacon receiver together with this

tracking device, enter 'BCRX.ftrack.fast' here, replace BCRX by the

device name of the beacon receiver. This tells the tracking engine to

perform a synchonous frequency tracking step on the beacon receiver

before each antenna tracking step.

config.bcrxFaultId Enter here the parameter ID of the beacon receiver fault, the tracking

unit shall monitor.

config.xDiameter This parameter tells the tracking device the width of the antenna dish.

The tracking device computes the azimuth tracking step size from this

parameter and the beacon frequency value.

config.yDiameter This parameter tells the tracking device the height of the antenna

dish. The tracking device computes the elevation tracking step size

from this parameter and the beacon frequency value.

longitude The antenna's longitude (degree east). Provide this value with an

accuracy of 0.01° to ensure a precise orbit to pointing calculation

latitude The antenna's latitude (degree north). Provide this value with an

accuracy of 0.01° to ensure a precise orbit to pointing calculation

altitude The antenna's altitude over sea. Provide this value with an accuracy

of 10 meters to ensure a precise orbit to pointing calculation

Built in analysis tools



The Antenna-Tracking device is capable to show two different types of diagrams which

support you to monitor and optimize the tracking behaviour.

The first diagram tool is the X/Y display of the antenna movements. This display works

completely autoscaled, it shows one green dot for each antenna position the tracking

memorizes (usually the recent 48 hours). The actual antenna pointing is marked with a

slightly larger yellow dot. After at least 24 hours of continous operation, the antenna position

dots give the curve of the daily movement of the satellite, from the antenna's angle of look.

With a mouse click to the diagram area, the display cas be switched into a Y/T diagram

showing the recent 48 hours. This condensed display of the azimuth, elevation and beacon

level variations over 48 hours is ment as an overview display. A second mouse click switches

back to the previous view.

The separate Y/T display window gives more detailed information about what the tracking

engine did during the recorded 48 hours. It provides variable scales, and permits to display

additional information. The display shows either the azimuth or the elevation pointing found

at the beginning of each each tracking step together with the beacon level measured at this

time. The following additional information may be included to the diagram:

If this toolbar button is pressed, the diagram shows the search step and the beacon level

change resulting from this as a dimmed peak at the left edge of each data point. You can

easily monitor the signal degradation which is caused temporarely by the tracking search

steps with this function enabled.

If this toolbar button is pressed, the diagram includes the evaulated peak positions. In

STEP track mode, this actually is the location where the antenna gets moved to. In

ADAPTIVE tracking mode, the antenna moves to the location resulting from the

mathematical model which is computed from the step track peaks. In the latter case, the

peak positions may be interptreted as the actual difference between the modeled pointing

and the peak position.

Recommended beacon receiver settings

Below some recommended settings for the sat-nms L-band beacon receiver for the use with

the tracking device are listed. These settings have proved to work satisfactory in most cases. If

you are using a third party beacon receiver, use analogous values a starting point.

Measurement

bandwidth

30kHz

Post detector filter 0.5 Hz

Frequency tracking OFF (the tracking device switches this ON/OFF automatically with a

sat-nms L-band beacon receiver)

2.2.1. Pointing-Robot

This page describes the device driver and the device window for the Pointing-Robot logical

device. This device lets you make a motorized antenna follow a satellite based on it's (known)



orbit position. For this the Pointing-Robot implements orbit position calculations based on

common ephemeris data models. The basic functions of a Pointing-Robot device are:

• Point the antenna to the nominal position of a satellite.

• Move the antenna along a satellite position calculated from ephemeris data.

• Move the antenna along a path given by a table.

The Pointing-Robot is part of the sat-nms ACU Indoor Unit. It supplements the sat-nms

ACU-ODM with the orbit calculation routines described below. The Pointing-Robot

principally works together with all drivers for antenna controllers which are part of the sat-

nms software. However some functions like automatically switching off the ACU's tracking

facility are uniquely designed for the sat-nms ACU-ODM.

Move the antenna along a satellite position calculated from ephemeris data

You can make the pointing robot follow a satellite position computed from usual ephemeris

data sets. The robot recognizes the following data formats:

Keplerian

elements

The robot recognizes and parses keplerian elements in the NASA 2-line

format. The two lines of element definition may be prepended by an additional

line with the satellite's name. A common source for Keplerian elements in this

format is www.celestrak.com. The pointing robot uses the NORAD SDP4

model to predict a satellite's position from this type of data.

Intelsat

elements

Intelsat publish ephemeris data for their communication satellites at their web

site. The data format and the mathematical model for this data is Intelsat

proprietary. The pointing robot recognizes this data type as well. You should

copy the complete text of the ephemeris data set into the entry field to make

the software recognize the data correctly.

Pointing the antenna to the nominal position of a satellite

If a single floating point number is entered to the ephemeris data field, the pointing robot

interprets this as a nominal orbit position of the satellite (°E).

Move the antenna along a path given by a table

The pointing robot is capable to move the antenna along a path defined in a text file table.

You either may copy the file to the IDU computer by means of FTP and enter the name of file

to the ephemeris field or you may enter or cot/paste the table directly to this field. If you do

the latter, the size of the table is limited to 32000 characters.

The format of the table must be as follows: It contains the data as a three or four column table.

Empty lines are ignored, comments starting with a '#' as well. The numbers in the table are

parsed as floating point numbers which only may consist of decimal digits, one decimal point

and an optional leading '-' if negative. The columns must be separated by an arbitrary number

of space or tabulator characters. They have the following meanings:

1 time stamp The time stamp must be a Julian date with the time of day coded as a



fraction of a day. Example: The Julian date for the common base of most

computer clocks (1970-01-01 00:00:00) is 2440587.5

2 azimuth

angle

The azimuth angle in degrees

3 elevation

angle

The elevation angle in degrees

4 polarization

angle

The polarization angle in degrees. This column is optional, no polarization

pointing is commanded if this column is missing.

Parsing order

If the pointing robot gets entered a new ephemeris data set, it tries to interpret the data in the

following way:

1. It checks if the data is a valid NASA 2-line data set. A satellite name before the 2-line

data is accepted and parsed separately if present.

2. It checks if the data contains valid Intelsat ephemeris data.

3. It checks if the data contains valid Eutelsat ephemeris data.

4. It checks if the first number in the first line of the data is a valid Julian date in the

range 2005 .. 2050. In this case the robot assumes, that the ephemeris data contain a

pointing table.

5. It checks if the first line of the data specifies an existing file (residing on the IDU

computer, therefore the file path should use Unix-style ('/') directory separators if

necessary. If there is the specified file, it is read and parsed as described above.

6. Finally, if nothing of the above mentioned formats did match, the robot tries to

interpret the first line of the data as the nominal orbit position of the satellite.

If all of the parsing attempts fail, the pointing robot reports the model type to be UNKNOWN.

Mostly this happens due to artifacts of previously entered elements which had not been

deleted before the new ephemeris data was entered / pasted.

Device window pages



device windows.

The main parameter page displays/controls the antenna pointing. Actual readings and set

points are shown in separate fields, so you can see where the antenna is going to while it

is moving.

The faults page.



page.





which must be set to make the software talk to the antenna controller.


antennaName The name of the antenna ODM device to control. With the sat-nms IDU, this

parameter is preconfigured to 'ODM' and should not be changed.

longitude The antenna's longitude (°E).

latitude The antenna's latitude (°N).

altitude The antenna's altitude over sea (m)

Remarks

The accuracy of the calculations made by Pointing-Robot depend on the following:

• The geodetic location of the antenna must be known very precisely.

• The antenna's azimuth axis alignment must be precisely perpendicular.

• The clock of the M&C computer must be set to UTC.

ors the fault states of a couple of devices, deriving from this the information whether to switch

the (usually transmit-) chain.

2.3. SatService-ACU-IDU This page describes the device driver and the device window for the SatService ACU/IDU

tracking controller (indoor unit). This driver allows the position and state of an sat-nms

tracking unit to be monitored via RS232 from a M&C system or an VLC.

As the sat-nms ACU/IDU tracking controller provides it's own HTTP based user interface, it

is recommended to install a link to the ACU user interface at the main task oriented screen of

the application. The Frame Button may be used to provide this function.

Device window pages



device windows.

The first parameter page displays the antenna pointing. No changes can be made with

this version of the device driver.

The second parameter page displays the tracking mode / state. Refer to the Antenna-

Tracking manual page for en axplanation of the tracking modes in particular.

The faults page.



page.




There are no special configuration settings neccessary to communicate to the SATNM ACU

indoor Unit. However, remember to set the line parameters for the serial interface to the

correct values: 19200,N,8,1.

2.4. SatService-ACU-ODM This page describes the device driver and the device window for the sat-nms ACU outdoor

module. The driver treats the ACU ODM as a plain antenna positioner, communicating via

Ethernet/HTTP to it. The configuration parameters of the ACU ODM are accessible through

the ACU web based user interface, they are not replicated as configuration parameters in the

M&C device driver.

Device window pages



device windows.

The main parameter page displays/controls the antenna pointing. Actual readings and set

points are shown in separate fields, so you can see where the antenna is going to while it

is moving.

The faults page.



page.



which must be set to make the software talk to the antenna controller.


address This is the only parameter that must be set. Enter the antenna controller's IP

address in 'dotted quad' notation here. Example: "192.168.2.81".

2.5. SatService-Beacon-Receiver This page describes the device driver and the device window for the sat-nms LBRX beacon

receiver.

Device window pages



device windows.



The first parameter page displays the receive level and lets you set the basic receive

parameters like frequency, bandwidth and input attenuation.

This page lets you configure the C/N measurement mode of the receiver and displays the

signal C/N if this mode is active.

This page contains the parameters to configure the frequency tracking facility of the

receiver.

The faults page.



page.



which must be set to make the software talk to the receiver.


address The IP address of the receiver to control.

loBandLo Enter the LO frequency for the lower frequency band here (MHz), if you want

to specify the receive frequency in terms of true RF receive frequency. Enter 0

if you want the receive frequency to be displayed as receiver input (L-band)

frequency.

hiBandLo Enter the LO frequency for the upper frequency band here (MHz), if you want

to specify the receive frequency in terms of true RF receive frequency. Enter 0

if you want the receive frequency to be displayed as receiver input (L-band)

frequency.

bandEdge Enter the edge between the receive frequency bands here (MHz). The receiver

applies the 'loBandLo' LO frequency if the receive frequency is below the edge,

the 'hiBandLo' LO frequency if it is above. If the 22kHzTone parameter is set to

AUTO, the 22 kHz ist set accordingly.

lnbVolt This parameter controls the LNB supply voltage provided by the receiver at it's

input connector. The following settings are available:

OFF The D/C voltage is completely switched off.

14V The LNB supply voltage is 14V

18V The LNB supply voltage is 18V

AUTO The LNB supply voltage is switched on, the voltage depends on the

'Polarization' parameter. The voltage is

14V for vertical polarization,

18V for horizontal polarization.

22kHzTone This parameter controls the presence of a 22 kHz tone on the LNB supply

voltage. The following settings are available:



OFF The 22 kHz tone is switched OFF.

ON The 22 kHz tone is switched ON.

AUTO The receiver automatically enables the 22 kHz tone depending on the

receive frequency set. The tone is

switched OFF for frequencies below the band edge,

switched ON for frequencies above the band edge.

The band edge is set with the 'bandEdge' parameter above.

vOutScale This parameter defines the slope of the receiver's voltage output in V/dB. The

output voltage has a range of 0 .. 10 V. Setting this parameter to 0.25V/dB lets

the analog output cover a dynamic range of 40 dB.

vOutOffse This parameter defines, which input level gives 0V output.

C/N Measurement Mode

In addition to the normal level measurement, the sat-nms LBRX beacon receiver is able to

perform C/N measurements. This is done by measuring the level of the received noise at a

frequency other than the receive frequency in regular intervals. Each measured signal level

then gets converted to a C/N value by referring it to the noise level value. While the receiver

measures the noise level, it freezes the displayed C/N value as well as the analog output

voltage for this time.

The behavior of the C/N measurement function is controlled by three operational parameters:

Parameter

Name

Description

C/N Noise

measurement

This parameter controls if the receiver shall perform a plain input level

measurement or a C/N measurement. The following measurement modes

are available:

OFF The receiver performs a plain level measurement.

IN The receiver measures the signal / noise ratio. The The C/N

measurement page shows the C/N value in dB. and the normalizes

C/No value as well.

Noise

Measurement

Frequency

This parameter specifies the frequency at which the receiver shall measure

the noise level at a certain interval. Like with the receive frequency, the

LO frequency settings made at the Setup page are taken into account also

for this frequency value.

To get reasonable results with a C/N measurement, you should consider

the following:

1. The receiver does not change the LNB frequency band setting

when it switches from the level measurement to the noise

measurement. The LNB probably would change it's gain in this

case. The noise measurement frequency hence must be in the same



frequency band as the receive frequency.

2. Measuring the noise level at the band edge may falsify the result

due to the LNB's band filter. The measured noise level may be too

low in this case.

3. You should verify with a spectrum analyzer, that no signal disturbs

the noise measurement at the selected frequency.

Noise

Measurement

Interval

This parameter defines the interval at which the receiver inserts noise

measurements in the C/N modes. The time is specified in seconds. 3600

secs being one hour is a suitable setting in most cases.

Frequency Tracking

The sat-nms LBRX beacon receiver using it's non-coherent receiver design, does not

automatically follow an input signal drifting in frequency like a PLL receiver would do. To let

the receiver compensate effects like an LNC frequency drift due to temperature or Doppler

frequency shift, a frequency tracking algorithm has been implemented in the receiver.

With frequency tracking enabled, the receiver tunes the receive frequency a small amount up

and down at certain intervals. Such a search step takes less than one second, while the

frequency is detuned, the level reading and the analog output of the receiver stays frozen.

The step size used for a frequency search step depends in the measurement bandwidth, the

receiver automatically selects the appropriate step size. Receiving a C/W signal, the receiver

software expects a signal degradation of 1..3 dB when the frequency has been tuned up or

down. The receiver evaluates the signal center frequency by comparing the measured level, at

the old frequency f, at f+d and f-d to the known shape of the filter.

The behavior of the frequency track facility is controlled by three operational parameters:

Parameter

Name

Description

Frequency

Tracking

This parameter switches the the frequency tracking facility of the receiver

ON or OFF. Please note, that switching off the frequency tracking does not



reset the frequency offset which is applied by the frequency tracking. To

reset the offset, set the receiver's frequency setting.

Frequency

Tracking

Interval

This parameter sets the interval on which the frequency tracking procedure

operates. The value is in seconds. Recommended settings are 15 seconds to

tune the receiver quickly to a frequency you do not know precisely. For

normal operation a frequency tracking interval of one hour (3600 secs) is

recommended.

Frequency

Tracking

width

With this setting you limit the frequency offset the frequency tracking

procedure may apply to the nominal frequency. The frequency tracking never

tunes the receiver to a frequency outside the specified range, a frequency

track fault is generated if the tracked frequency reaches the limit.

2.6. SatService-Power-Sensor This page describes the device driver and the device window for the sat-nms Power Sensor.

Device window pages



device windows.

This page shows the power reading and lets you set the power sensor's operational

parameters.

The faults page.



page.



which must be set to make the software talk to the receiver.


address This is the only parameter that must be set. Enter the power sensor's IP address in

'dotted quad' notation here. Example: "192.168.2.81".

sat-nms ACU-IDU Antenna Control System –Indoor Unit … ... TCP/IP). Any tracking functions ......

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